Froze explaining my OWN project in an interview. Knew the code cold, still blanked

Behavioral round, they asked me to walk through a project on my resume, something I literally built and shipped. My brain just emptied. I stumbled through it like I'd read about it in a blog post. Meanwhile I can debug that codebase in my sleep.

Afterward I realized I'd never actually said any of it out loud. I know the code, I'd never practiced the story. Now I rehearse a 90-second version of each project (problem, what I did, what broke, what I'd change) before every interview. Anyone else get wrecked by the easiest possible question?